I purchased some .22 Rimfire ammo several years ago, probably about 5, and when I went to the range a few days ago, over half of the ammo would not fire. I tried it in 2 firearms with the same results. Both firearms made nice indentations in the rim of the ammo. I tried rotating the ammo so the pin would strike another part of the rim and a few of the rounds did fire. This is not a cheap brand. The ammo is a high grade from a name brand. What gives?

when it gets old the primers will dry out an it will not fire, the primer power will fall out of the rim in the case, an will not fire, common accurrence with old 22 rimfire, if they are keep in a ammo can with a tight seal, it can be prolonged but old age will catch up at some time of it life, an some times it takes a long time for this to happen,
this is what I have ben told
SID

I'm betting it was Remington ammo. Remington "golden bullet" and especially bulk pack is notorious for failure to fire. If the ammo is good to start with, and stored properly, there is no shelf life for ammo.

I thought that with my Blazer 9mm ammo and self-defense ammo as well, moved to Germany for 5 plus years and returned - fired that ammo - no issues. Glock was very much missed in that time. The ammo and gun was secured in a locked fireproof safe box.

I've shot the old Winchester Super X .22LR ammo that was at least 20+ years old with no issues whatsoever. Matter of fact the stuff grouped pretty darn good. Went with the newer stuff (Winchester Super X - X22LR) and it did not perform as good as the old stuff did.